Foundation piles



0d- 5, 1964 sHulcHlRo sA'ro E'rAL 3,151'464 FoUNDA'rIoN PILEs Filed May 23. 1980 s shee'zs-sheet 1 INVENTORS 67/ U/cH/eo (Skra 0d- 6, 1964 sHulcHlRo sATo ETAL 3,151,464

FOUNDATION PILES Filed May 23, 1960 5 Sheets-Sheet 2 Oct. 6, 1964 SHU|CH|R0 sA'ro ETAL 3,151,464

FOUNDATION PILES '-5 Sheets-Sheet 3 Filed May 23, 1960 DID M z 0%- bbm voo 3.00

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United States Patent O 3,151,464 FOUNDATIN PILES Shuiehiro Sato and Jiro Nakaoka, Tokyo, Japan, assignors to Nippon Sharyo Seizo Kaisha, Ltd., Atsuta-ku, Na' goya-shi, Japan, a company of Japan Filed May 23, 1960, Ser. No. 31,149 Claims priority, application Japan May 25, 1959 1 Claim. (Cl. 61-53.58)

This invention relates to a method for constructing foundation piles of a large length and to pile units for use in performing the same.

For constructing foundation piles of a large length, it has hitherto been practised either to connect precast concrete pile units on succession on the field, or to insert reinforcement in the previously prepared holes and then to pour concrete thereinto whereby a pile is constructed underground. It is difticult, however, to obtain connection, strong enough to resist ground settlement, with a pile formed by the former method, namely by connecting precast concrete pile units. Also, according to the latter method of constructing a pile underground, casing tubes must be used at the places where the ground is soft or where underground water is abundant, for fear that the pile may not be formed.

The object of the present invention is to provide an in-place method for constructing a concrete foundation pile by eliminating the above-mentioned defects.

In order to accomplish the above object, the invention is characterized in that precast concrete pile units, each having a grout hole at their center and a plurality of longitudinal grooves at their outer surfaces or having a grout hole at their center and a plurality of longitudinal holes passing therethrough, are piled up in succession in the previously prepared holes in the soil in such a way that their sections will co-incide; thereafter, aggregates are filled in said grooves or in said holes of said pile units; and then cement milk is poured under pressure into the space left in said filled in aggregates and into the space left at the connecting parts of said pile units, and into the space left at the bottom of the constituted pile.

The invention is hereunder explained with reference to the attached drawings which illustrate the mode of the method of the present invention and certain embodiments of the pile units for use in the present invention. It must be noted, however, that such embodiments are illustrated by way of examples, not limiting the scope of the invention.

In the drawings, FIG. 1 shows a plan view of a precast concrete pile unit for use in the method of the invention,

FIG. 2 is a perspective view of the pile unit shown in FIG. l, a part thereof in section,

PIG. 3 is a partial sectional view at line A-A of FIG. 1,

FIG. 4 is a perspective view of a joint for pile units shown in FIGS. 1-3,

FIGS. 5 and 7 show the method for inserting pile units in succession in the previously prepared holes in the soil,

FIG. 6 is a front view of a quick release device for use in the method of the invention,

FIG. 8 illustrates the mode of how the aggregates are Patented Oct. 6, 1964 filled in the side grooves of pile units and how these are grouted,

FIG. 9 shows the foundation pile constructed underground in accordance with the method of the invention,

FIG. 10 is a perspective view of a pile unit having a cover plate at one of its grooves, and

FIG. 11 is a plan view of another embodiment of pile units.

In FIGS. 1 and 2, the precast concrete pile unit 1 is formed as cylindrical and has a plurality of (for example four) longitudinal grooves 11 at its outer surface. In the ribs 12, steel reinforcements 13 are buried. In the center of the pile unit 1, a grout hole 14 passing through the whole length thereof is provided. At the two ends of the pile unit 1, around said hole 14, is provided a socket 15 which can receive one half of the height of the joint 2 shown in FIG. 4. And, at the upper end surface of the pile unit 1, a pair of hanger bolts 16 and a pair of grooves 17 are provided. Since the top of said hanger bolts 16 shall not project over the upper end surface of the pile unit 1, said grooves are provided for hanging Wire ropes to said bolts 16. From the grout hole 14, a certain number of grout holes 18 are branched to open to the grooves 11.

The joint shown in FIG. 4 is' of steel. Its form is tubular, the inner diameter of which is equal to the diameter of the central hole 14 of pile unit 1, and on its outer surface longitudinal ribs 21 are provided. Several grout holes 22 are also provided on its cylindrical surface at the position equidistant from the two ends of the tube. The said joint 2 is so designed that the bond strength of the jointed parts of pile will be equal to the strength of section of the pile unit 1 when the two adjoining pile units are moulded together with cement milk at a later stage. The ribs 21 restrict the direction of end surface of each of pile units and align the grooves 11 through all the pile units piled up.

As shown in FIG. 5, when the pile units 1 are laid in the previously prepared hole 3, the jointed steel pipe 31 is taken down into said hole 3 for gniding said sectional pile units in the hole. At the lower end of said pipe 31, the positioning frame 32 is provided, which places the steel pipe 31 exactly at the center of the hole 3. The said frame 32 need not be strong. It may be of a simple structure of metal Wire. It will be left at the bottom of the hole 3 when the laying operation of the pile is completed and the pipe 31 is pulled out.

When the pile units 31 are laid in succession in the hole 3 with said steel pipe 31 as guide, it may be possible that the hole 3 is filled up with sheathing material 4, such as slurry. In such case, said sheathing material 4 does not obstruct the laying operation of pile units, because such material will go up through the groove 11 of the pile units 1. It is hitheuto known that, when the foundation pile is laid in the hole previously dug in the soil, no suflicient skin friction sp roduced until the pile reaches a certain depth, and the wall of the hole 3 falls in, due to free falling of the pile. In the above case, according to the method of the present invention, the lower end of the pile unit 1 is hung by means of the hoist wre 51, and the guide pipe 31 is passed through the central hole 14 of the pile unit 1, so that the pile unit 1 may be lowered down gradually, guided by said pipe 31. The wire 51 and the wire 53 are connected together by the quick release device 52 which can be contained in the grooves 11. The wire 53 is led to a Winch (not shown) through the sheave 54 which is provided at a height which makes it possible to connect one pile unit 1 with the following pile unit 1 on the ground, and the pile units are lowered down with their weight loaded on said Winch.

When the first pile unit 1 is lowered down to the ground level, the joint is set to the socket 15 of the pile unit 1, and the lower socket 15 of the second (following) pile unit 1 is set to said joint 2. Thus, the first and the second pile units are piled together. By repeating the above operation, several pile units are made to be lowered in the soil in the state these are piled up together. By doing so, the skin friction will be sufficient to hold said several pile units piled together. The quick release device 52, shown in FlG. 6, is of the wall known mechanism. Namely, it can be released at will at its loaded state by Operating on the ground, and when the skin friction is suiicient to hold several pile units, as above-mentioned, the Wire 53 and the device 52 are pulled up to the ground surface, leaving only the Wire or sling 51 at the lower end of the first pile unit which is situated lowest.

In the quick release device shown in FIG. 6, a hook 522 is pivoted to the body 521 with a pin 523. The pawl at the end of said hook 522 engages the pawl of the trip lever 525 and tcnds to turn counter-clockwise the lever 525 around the pin 524 under the loaded state. However, as the end of the lever 52.5 is stopped by the stop pin 527 which slides in the guide 526, the hook 522 cannot be released, and holds the load. When the Wire 528 is pulled up, the stop pin 527 disengages the lever 525, so that the hook 522 and the pawl of the lever is also disengaged and the book 522 is released.

In order to force the pile units further down in the hole 3 the aforementioned several pile units piled together, held by skin friction, the'thrust yoke 6 is put on the top of the uppermost pile unit, the rope 61 is connected to the two ends of said yoke 6, and one end of the rope 61 is led to a Winch (not shown) through the sheave 62 fixed on the ground or pulled by a weight. On the top of the uppermost pile unit, the annular washer 63 having a spherical upper surface is put, said spherical surface being engaged with the corresponding spherical surface provided on the thrust yoke 6, so that the thrust force may be transmitted smoothly to the pile unit 1. Between the washer 63 and the top surface of the pile unit 1, a soft material, such a fiber, is placed for evenly distributing the pressure.

After the pile units piled together are laid in the hole 3, the aggregates 7 are filled in the grooves 11 longitudinally formed on the side surfaces of pile units, all through the length thereof. rl`his is shown in FIG. 8. If necessary, reinforcements may be inserted in the grooves 11. By washing the bottom of the pile unit lowest placed and, if necessary, certain parts of the grooves 11 of all the pile units with water under pressure or compressed air or both. The steel tube 31 and the hole 14 may be useful for this purpose. Then by pouring cement milk under pressure through the central hole 14 of the pile units, the required amount of cement is filled in the pace left in the aggregates 7 in the grooves 11 through the grout hole 18, in the ends 33 through the hole 14, and also in the connecting parts of the pile units |through the grout hole 22, as shown in FIG. 8, FIG. 9 shows the pile units piled together, fonning a foundation pile completed in the soil.

It can easily be recognized that the foundation pile formed by using the pile units 1 of the shape shown in FIGS. 1 and 2 is not a column having a smooth surface, but is a column having an irregular surface, as shown in FIG. 9, due to grouting pressure of cement milk. Such form is advantageous because it increases the skin friction and therefore increases the load bearing capacity of the pile. In case there is a fear that soft soil and sand on the side of the hole 3 may fall in, more especially when the above washing process is performed, and may plug up the grooves 11, or in case it is though undesirable that swelling caused by grouting pressure of cement milk may be conspicuous at certain places, the corresponding parts of the grooves 11 may be covered with a thin cover plate 8 made of steel or the like, as shown in FIG. 10, and said plate 8 may be fixed onto the ribs 12 with concrete nails 81. It may happen that the soil condition requires a load bearing capacity at the pile bottom only, and the bearing capacity due to skin friction is undesirable. In such case, the above cover plate 8 may be applied to the whole length of the pile, or the pile units 111 provided With a plurality of longitudinal holes 112, of which the section is shown in FIG. 11, may be used.

The advantages of the method of the present invention can be resumed as follows:

Since the pile units may be produced in a factory by precast method, these can be strong, can be transported, hoisted and erected easily. Compared with a precast concrete pile hitherto used, the total length of the foundation pile in accordance with the present invention can be chosen at will in conformity with the requirement, Also, when the hole is iilled with a certain sheathing material, it has been necessary to find the leakage of such sheathing material for inserting the hitherto used foundation pile. By using the method of this invention, such necessity is eliminated.

According to the hitherto practised method, the strength at the connecting parts may be insufiicient due to simple connection of piles. According to the present method, the strength after completion of pile can be made satisfactory, due to the fact that the pile units are formed into one body by means of aggregates and cement milk filled in. Furthermore, when the surface of the pile is made irregular, its load bearing capacity can be made still larger. In case of necessity, the surface of the pile may be partially irregular.

The pile units of the present invention can be used as sheath pile, by selecting properly the shape of plane surface of pile units and by connecting these units side by side With each other.

Contrary to the hithento practised method, which consists in laying reinforcements in the hole and pouring concrete thercinto, thereby constructing a foundation pile in the soil, the method of the present invention can surely be perforrned, irrespective of the quality of soil.

We claim:

A foundation pile consisting of a series of concrete pile units connected to make up a column, all of said units having the same cross sectional configuration, each unit of the column having a central portion with a plurality of alternate longitudinal projcctions and recesses around their perimetral surface forming vertically disposed continuous longitudinal projections on the exterior of the column with alternate upwardly open grooves therebetween, said grooves being of such depth from an imaginary circle engaging the perimeter of said projections to receive gravel from the surface of the ground, a Vertical grout passage extending through and pre-positioned in the central portion of each unit and vertically aligned throughout the column, a socket in each end of the central portion of each unit concentric with and larger than the ends of said adjacent grout passages, an independent tubular joint member in each of the adjacent sockets connecting adjacent units in the column and having a length substantially twice the depth of each socket, at least one longitudinal rib on the exterior of each joint member, at least one longitudinal slot in the wall of each socket receivng the rib of, its respective joint member, said slot being orented in the same peripheral position with respect to a projection in each unit to lock adjacent units against rotation and vertically align the longitudinal projections and the alternate grooves of the units forming the column, a grout bore in each joint member mating in Vertical alignment with the grout passages of the units throughout the column, a series of vertically spaced lateral grout passages in each unit extending from said Vertical grout passage of the column to each of the upwardly open grooves, and a lateral grout passage from said grout bore in each of said tubular joint members and opening to said upwardly open grooves and between adjacent ends of connected pile units in the column.

References Cited in the file of this patent UNITED STATES PATENTS 858,742 Moran July 2, 1907 1.542,037 Cortes Iune 16, 1925 1,979,547 Hood Nov. 6, 1934 6 Iorgensen Dec. 31, 1935 Watt July 14, 1936 Montague June 5, 1951 Mueller Feb. 16, 1960 Mueller Sept. 13, 1960 FOREIGN PATENTS France Aug. 22, 1936 Sweden Dec. 21, 1937 Austria Feb. 25, 1958 France Apr. 21, 1954 

